Department Of Environmental Science And Technology

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Author: search.filters.author.Rathi, ManohariSubject: search.filters.subject.Rhizosphere

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    Role of Quorum Sensing in the Survival of Rhizospheric Microbes
    (Springer Nature, 2022-01-01T00:00:00) Rathi, Manohari; Manchanda, Geetanjali; Singh, Raghvendra Pratap
    Quorum sensing (QS) signaling is a cell-to-cell communication or coordination at microbial population level. However, the ecological role of QS in complex or multi-species communities, principally in the milieu of community assemblage, has neither been experimentally discovered nor theoretically revealed. QS comprises the production of secreted signals (diffusible), which can diverge across diverse types of microbes. Over the past decades, there has been a significant accretion of data of the molecular mechanisms, gene regulons, signal structures, and behavioral responses related with QS systems gained. More recent studies have focused on understanding quorum sensing in the context of bacterial sociality. Studies of the role of quorum sensing in cooperative and competitive microbial interactions have discovered, how QS coordinates interactions both within and between the species. Such studies of quorum sensing as a social behavior have relied on the development of �synthetic ecological� models that use nonclonal bacterial populations. Hence, the aim of this chapter is to understand how microbes might interact with one another in the plant root�associated soils using QS system. � The Editor(s) (if applicable) and The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2021.
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    Copper-tolerant rhizosphere bacteria—characterization and assessment of plant growth promoting factors
    (Springer, 2017) Rathi, Manohari; Yogalakshmi, K. N.
    Remediation of heavy metal contaminated soil is a major problem or concern worldwide. Heavy metal accumulation in the soil is increasing day by day by industries, mines, agriculture, fuel combustion and municipal waste discharge. Such contaminated soils harbour a large number of resistant microbial populations. Screening and isolation of such microbes would be utilized for natural remediation of metal contaminated soils. Therefore, in the present study, highly copper-tolerant bacteria from rhizosphere soil of Cynodon dactylon grown in brass effluent contaminated soil were isolated and assessed for plant growth promoting factors. A total of 61 isolates were isolated from the rhizosphere of three contaminated sites. Six highly copper-tolerant isolates named as MYS1, MYS2, MYS3, MYS4, MYS5 and MYS6 were isolated through enrichment in copper containing nutrient broth. 16S rRNA analysis revealed that the isolates were from genera Stenotrophomonas and Brevundimonas and belong to classes Alpha Proteobacteriacea and Gamma Proteobacteriacea, respectively. Strain MYS1, MYS2 and MYS4 showed 95–99% similarity with Stenotrophomonas acidaminiphila, strain MYS3 and MYS5 showed 99 and 97% similarity with Stenotrophomonas maltophilia and Stenotrophomonas sp. Strain MYS6 showed 94% similarity with Brevundimonas diminuta. All the rhizobacteria showed plant growth promoting traits such as production of siderophores, indole acetic acid (IAA), phosphate solubilization and 1-aminocyclopropane-1-carboxylic acid (ACC) deaminase activity. From this study, we can conclude that all the isolates possess copper resistance and potential for phytoremediation of copper polluted soils.